1. Programming Stream Manipulators

2. COMP102 Prog. Fundamentals I: Stream Manipulator Slide 2 Stream Manipulators in iostream.h Library I/O stream manipulators modify the behavior of insertions ( > ). l Examples: endl, flush oct, dec, hex (persistent effect: a change stays effective until another change is requested) int i = 10; cout << i << ” ” << i + i << endl; // 10 20 cout << oct << i << ” ” << i + i << endl; // 12 24 cout << hex << i << ” ” << i + i << ” ” << dec << i << endl; // a 14 10 decimal: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 octal: 0 1 2 3 4 5 6 7 10 11 12 13 14 15 16 17 20 21 22 23 24 Hexdecimal: 0 1 2 3 4 5 6 7 8 9 a b c d e f 10 11 12 13 14

3. COMP102 Prog. Fundamentals I: Stream Manipulator Slide 3 Number Systems l Octal n Base 8 n 8 symbols l Hexadecimal n Base 16 n 16 symbols n More compact representation of the binary system Decimal Octal Hexadecimal 00 00 0 01 01 1 02 02 2......... 07 07 7 08 10 8 09 11 9 10 12 A 11 13 B......... 15 17 F 16 2010......... 749 13552ED

4. COMP102 Prog. Fundamentals I: Stream Manipulator Slide 4 More Stream Manipulators in iomanip.h Library l #include Output manipulators (all except setw() are persistent): setprecision(d) - set number of significant digits to d ( d = 0 for default precision); enforce d decimal places by setting the I/O flag fixed setw(w) - set field width to w (or minimally larger than w to display the value correctly) setfill(c) - set fill character to c setiosflags(f) - set flag f to 1 resetiosflags(f) - set flag f to 0

5. COMP102 Prog. Fundamentals I: Stream Manipulator Slide 5 Formatting Flags (1/2) ios::fixed n Fixed-point notation (default: not set) Example: 12.34 ios::scientific n Floating-point notation (default: not set) Example: 1.234e+001 ios::showpoint n Decimal point and trailing 0’s (default: not set) Example: 12.00

6. COMP102 Prog. Fundamentals I: Stream Manipulator Slide 6 Formatting Flags (2/2) ios::showpos A plus ( + ) sign is shown before positive numbers (default: not set) Example: +12 ios::right Right-justified format when used with setw() (default: set) ios::left Left-justified format when used with setw() (default: not set)